Directed self-assembly (DSA) is currently being explored for the formation of features at sub-lithographic pitch (i.e., at a pitch greater than that achievable using conventional lithography techniques). For instance, Yamaguchi et al., “Two-Dimensional Patterning of Flexible Designs With High Half-Pitch Resolution by Using Block Copolymer Lithography,” Adv. Mater., Volume 20, Issue 9, pp. 1684-1689 (May, 2008) (hereinafter “Yamaguchi”), the contents of which are incorporated by reference herein, describe use of block copolymer self-assembly in conjunction with high-precision electron beam lithography to create two-dimensional self-assembly of diblock copolymers. According to the procedures in Yamaguchi, both bent lamellae and concentric cylinders were formed on a semiconductor substrate using hydrogen silsesquioxane (HSQ) guiding patterns. To date, however, DSA-based patterning techniques have been limited to producing simple shapes on a substrate, such as the bent lamellae and concentric cylinders described in Yamaguchi.
Accordingly, techniques for fabricating functioning, high-level devices with DSA would be desirable.